Process for refining petroleum products



Nov. 17, 1953 A. GISLON ETAL 2,659,691

PROCESS FOR REFINING PETROLEUM PRODUCTS Filed Dec. 15, 1949 SWEETENEDGASOLINE GAS OUTLET DEOANTER GAS SEPARATOR AIR INLET REGIROULATEDTREATING SOLUTION CHARGE [2 VOLUME GASOLINE d VOLUME TREATING SOLUTIONcouTAmme= METHANOL 25 PARTS WATER I80 PARTS cAT-ox 0.5 PARTS WETTINGAGENT 0.2 PARTS INyENTO 5 Andre Q05 on da s'gph Quz/guerez A OR sPatented Nov. 17, 1953 PROCESS FOR REFINING' PETROLEUM PRODUCTS AndrGislon, Paris, and Joseph Quiquerez, Saint- Cloud, France, assignors'to;Societe Anonyme dite Compagnie Francaise de Raflinage, Paris, France, acorporation of France Application December 15, 1949, Serial No. 133,058

19 Claims.

It is known that the mercaptans in petroleum products, and in particularin light products such as gasolines, naphthas, solvents, kerosenes, areeliminated by means of a refiningoperation which is generally known bythe name of sweetening and which consists in converting the mercaptansinto disulfides by oxidation. The usual process for efiecting thisrefining is the plumbite process which comprises treating the petroleumproducts in question with a solution of alkaline plumbite in thepresence of sulfur, the successive reactions being: formation of leadmercaptides, oxidation of same by means of sulfur with formation oforganic disulfides and lead sulfide, and finally regeneration of theplumbite solution through oxidation by air of the lead sulfide in analkaline medium.

The recognized drawbacks of this process are also known: since leadmercaptide is soluble in hydrocarbons, the lead sulfide is formed in thecolloidal state in said hydrocarbons; since the decantation is slow, inorder to accelerate it, it is necessary to add an excess of sulfur andthis excess may be detrimental as regards corrosion, the octane numberand susceptibility to lead. Furthermore, the exact quantity of sulfur tobe used is often difiicult to ascertain and the regeneration of theplumbite is a slow and comparatively costly operation. e

Other processes, in which the oxidation is effected by means of metallicsalts such as copper salts, also have serious drawbacks owing to thesolubility of the metalic salt in the hydrocarbons treated.

Endeavours have been made in various manners to effect the oxidation ofthe mercaptans by means of air, but heretofore no simple process hasbeen discovered.

We have noted that certain organic substances and more especiallyorganometallic compounds with chelated bonds, have the property ofabsorbing oxygen from air and of releasing it under certain conditions;such products include hemoglobin amongst the natural products, and also,amongst the synthetic products, the iron-indigo complex disalicylalethylene diamlno cobalt I C=1TT N=c CH2H2 or bi-disalicylal ethylenediamine-aquo dicobalt In a general manner, these compounds, some ofwhich have now become industrial, absorb the oxygen from air at ordinarytemperature and/or under pressure and release it in the pure state,either by increase of temperature, or in vacuo.

We have however observed this unexpected fact, viz. that in the presenceof reducing agents. and in particular of mercaptans, the absorption andthe exchangeof oxygen are effected at the same temperature. The organiccompounds in question behave in this case like real oxidation catalystsand the invention essentially lies in the novel application of saidcompounds to the elimination of the mercaptans contained in petroleumproducts.

In order to simplify the terminology, the compounds in question arehereinafter designated by the word cat-ox which is an abbreviation of 1oxidation catalyst.

Thus, if 1 litre of gasoline containing 0.02% of sulfur in the form ofmercaptans isshaken in air inthe presence of 1 gram ofcat-oxibidisalicylal ethylene diamineaquo dicobalt, for example) it isfound that, after 15, 30, 45 minutes, the proportion of mercaptans issuccessively 0.008; 0.005, 0.003 per cent. The gasoline can then beseparated, the same quantity of gasoline containing mercaptans added,and the operation repeated. It is again found that there is a gradualoxidation of the mercaptans, and this takes place several timesconsecutively. This exepriment clearly shows the catalytic effect ofthe'cat-ox since it is well known that if gasoline containing mercaptansis merely shaken in air, such a result is not obtained.

However, in this method of operation, the reaction speed is very slowand would not allow of the process being worked industrially.

We have furthermore observed that this reaction speed is considerablyincreased if certain organic compounds which are solvents for catox areadded to the hydrocarbon; amongst such compounds mention may be made,without this list being limitative, of methyl alcohol, ethyl alcohol,isopropyl alcohol, butyl alcohol and the like, ketones, dioxane,pyridine, and the like.

Thus, if the foregoing test is repeated by treating 1 litre of gasolinecontaining 0.02% of sulfur in the form of mercaptans with air in thepresence of 1 gram of cat-ox, after adding 1 cubic centimeter ofmethanol, it is found that in five minutes the oxidation of themercaptans is complete.

The same effect is obtained in the presence of water, that is to say ifan emulsion of hydrocarbon containing mercaptans to be oxidized and asolution or a dispersion of cat-ox in a mixture of alcohol and water,acetone and water, pyridine and water, or the like, is treated with air.

From an'industrial standpoint this modification of the invention hasnumerous advantages:

(a) The solvent is not lost in the hydrocarbon phase;

(1)) No catalyst is lost by being carried away in the hydrocarbon;

(c) The quick decantation of the aqueous ,phase carries away the cat-oxin the hydroorganic medium and makes it possible to avoid any filtrationof the hydrocarbon;

(d) It is possible to operate without a solid dispersion by using thesolution of the catalyst in the hydro-organic medium chosen. 7

Various non-limitative examples of applications of the inventionaccording to this modification are given hereinafter:

Example 1 A solution of 0.500 g. of cat-ox in 20 cubic centimeters ofmethanol and 180 cubic centimeters of water is prepared. The quantity ofactive oxygen in this solution is 25 mg. and can oxidize 100 mg. ofsulfur in the form of mercaptan. 200 cubic centimeters of this mixtureare shaken in the presence of air with 250 cubic centimeters of heptanecontaining 281 mg. of butyl-mercaptan. After 15 minutes allow to decant;separate the layer of heptane which does not contain any more mercaptan(Doctor test negative). Add the same quantity of heptane and mercaptanto the hydro-alcoholic phase; the mixture is sweet again after 15minutes. The operation can be repeated 30 times without the activity ofthe hydro-alcoholic solution of cat-ox being decreased.

Example 2 240 cubic centimeters of the same hydro-alcoholic solution ofcat-ox were used for treating as in the previous example 250 cubiccentimeters of Irak distilled gasoline containing 0.0336% of sulfur inthe form of mercaptans. After 25 minutes the gasoline was sweet. Thegasoline was separated and the same quantity of gasoline treated again.The operation Was repeated 25 times without observing any decrease inthe catalytic properties.

We have furthermore found that the speed of reaction is increased if thecontact between the phases is improved by adding a surface-active orwetting agent as is apparent in the next example.

Example 3 If 250 cubic centimeters of gasoline containing 82 mg. ofsulfur in the form of mercaptans are treated in air with 200 cubiccentimeters of a hydro-alcoholic solution containing 0.423 g. of cat-0x,the gasoline becomes sweet after 25 minutes. The same test was repeated,adding 1 per mil of sodium isopropyl-naphthalene-sulfonate to theaqueous phase; the oxidation of the mercaptans was completed in 10minutes.

The addition of any other surface-active or wetting agent, and inparticular a sodium sulforicinate, produced similar results.

Furthermore, it was observed that the addition of such a surface-activeor wetting agent favors the breaking up of the gasoline-aqueous solutionemulsion and accelerates the separation of the phases.

The speed of reaction is proportional to the ratio between the quantityof catalytic oxidation agent and the quantity of mercaptan to beoxidized, as shown by the following example:

Example 4 65 cubic centimeters of gasoline containing 15 mg. of sulfurin the form of mercaptans are treated in air with 220 cubic centimetersof a hydro-acetone solution containing 1.6 per mil of cat-ox containing5% of active oxygen and 1 per mil of sulforicinate. sweetening isobtained in 15 minutes.

If only 30 cubic centimeters of gasoline are treated with the samevolume of the same solution, sweetening is obtained in 3 minutes.

Example 5 The reaction can be carried out in a continuous manner, and byway of example the following apparatus and process are described withreference to the accompanying drawing.

1 volume of a solution comprising 25 parts by weight of methanol, partsof water, 0.5 part of bi-disalicylal ethylene diamine aquo-cobalt, 0.2part of sodium butylnaphthalene sulfonate and a volume of gasoline to berefined, are discharged per unit of time into a static mixer A by meansof a pump B. A quantity of air that corresponds at least to the quantityof sulfur to be oxidized is blown in at the bottom of the mixer. Afterpassing through a gas remover C in which the excess of air is separatedat b, the emulsion of the liquid phases is conveyed to a decantationtower D, at the top of which the sweet gasoline is continuously removedat c; at the bottom of the tower the hydro-alcoholic phase containingthe catalyst is exhausted by the pump B and discharged into the mixerafter adding the gasoline to be treated which is admitted at d.

By way of a modification, it is possible to use an excess of cat-oxdispersed in the hydro-alcoholic phase, so that the same is constantlysaturated; it is also possible to cause the gasolinemethanol-wateremulsion to flow towards a solid mass of cat-ox while air is beingblown; all these techniques also produce the sweetening of the gasolinetreated.

What we claim is:

1. A process for refining petroleum products, which comprises effectingthe oxidation of the mercaptans contained in said products by the actionof oxygen in the presence of organicchelate compounds that have theproperty of absorbing oxygen from air and of releasing it in a purestate, said chelate compounds having metallic constituents and saidchelate compounds behaving in this case as oxidation catalysts.

2. Process according to claim 1, wherein the absorption and exchange ofoxygen are efiected without change of temperature or pressure.

3. Process according to claim 1, wherein the oxidation is efiected inthe presence of a third substance chosen among the solvents for thechelate compound which is used.

4. Process according to claim 1, wherein the oxidation is effected inthe presence of an alcohol.

5. Process according to claim 1, wherein the oxidation is effected inthe presence of a ketone.

6. Process according to claim 1, wherein the oxidation is effected inthe presence of a solution of the compound used in a mixture of waterand an organic solvent for said compound.

'7. Process according to claim 1, wherein theoxidation is effected inthe presence of a dispersion of the compound used in a mixture of waterand an organic solvent for the said compound.

8. Process according to claim 1, wherein the oxidation is efiected inthe presence of a solution of the compound used in a mixture of waterand an organic solvent for said compound and in the presence of asurface active compound.

9. Process according to claim 1, wherein the oxidation is effected inthe presence of a dispersion of the compound used in a mixture of Waterand an organic solvent for said compound, and in the presence of asurface active compound.

10. Process according to claim 1, which is carried out in a continuousmanner.

11. Process according to claim 1, which is carried out in adiscontinuous manner.

12. Process according to claim 1, which is carried out at ordinarypressure.

13. Process according to claim 1, which is carried out at a pressurethat difiers from ordinary pressure.

14. The process of refining liquid petroleum products which comprisesoxidizing mercaptans contained in said products by the action of oxygenin the presence of a catalyst which is comprised of cobalt and organiccomponents which react to form a compound having a chelate bond.

15. The process of refining liquid petroleum products which comprisesoxidizing mercaptans contained in said products by the action of oxygenin the presence of a catalyst which is comprised of disalicylal iminocobalt.

16. The process of refining liquid petroleum products which comprisesoxidizing mercaptans contained in said products by the action of oxygenin the presence of a catalyst which is comprised of iron and organiccomponents which react to form a compound having a chelate bond.

17. The process of refining liquid petroleum products which comprisesoxidizing mercaptans contained in said products by the action of oxygenin the presence of a catalyst which is comprised of disalicylal ethylenediamino cobalt.

18. The process of refining liquid petroleum products which comprisesoxidizing mercaptans contained in said products by the action of oxygenin the presence of a catalyst which is comprised of lei-disalicylalethylene diamine-aquo dicobalt.

19. The process of refining liquid petroleum products which comprisesoxidizing mercaptans contained in said products by the action of oxygenin the presence of a catalyst which is comprised of the iron-indigocomplex NH NH/ 2,. NH& )NH 0 oo oo ANDRE GISLON. JOSEPH QUIQUEREZ.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 1,081,801 Wohl Dec. 16, 1913 2,302,352 Schultze Nov. 1'7, 19422,450,276 Folger Sept. 28, 1948 2,494,687 Bond Jan. 17, 1950 OTHERREFERENCES Calvin et al. J. A. C. 53., vol. 68, pages 2254 to

1. A PROCESS FOR REFINING PETROLEUM PRODUCTS, WHICH COMPRISES EFFECTINGTHE OXIDATION OF THE MERCAPTANS CONTAINED IN SAID PRODUCTS BY THE ACTIONOF OXYGEN IN THE PRESENCE OF ORGANICCHELATE COMPOUNDS THAT HAVE THEPROPERTY OF ABSORBING OXYGEN FROM AIR AND OF RELEASING IT IN A PURESTATE, SAID CHELATE COMPOUNDS HAVING